首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1321600篇
  免费   99023篇
  国内免费   1781篇
耳鼻咽喉   17023篇
儿科学   42513篇
妇产科学   36185篇
基础医学   196709篇
口腔科学   35724篇
临床医学   123871篇
内科学   259215篇
皮肤病学   28079篇
神经病学   107552篇
特种医学   48641篇
外国民族医学   270篇
外科学   187770篇
综合类   26655篇
现状与发展   3篇
一般理论   644篇
预防医学   110033篇
眼科学   29185篇
药学   96205篇
  7篇
中国医学   2089篇
肿瘤学   74031篇
  2019年   10957篇
  2018年   14700篇
  2017年   11234篇
  2016年   12234篇
  2015年   14078篇
  2014年   19649篇
  2013年   29921篇
  2012年   41049篇
  2011年   43651篇
  2010年   25149篇
  2009年   24232篇
  2008年   41085篇
  2007年   43869篇
  2006年   43468篇
  2005年   42692篇
  2004年   41003篇
  2003年   39114篇
  2002年   37937篇
  2001年   56654篇
  2000年   57549篇
  1999年   48799篇
  1998年   14124篇
  1997年   12841篇
  1996年   13174篇
  1995年   12451篇
  1994年   11592篇
  1992年   38657篇
  1991年   38146篇
  1990年   36870篇
  1989年   35638篇
  1988年   33093篇
  1987年   32408篇
  1986年   30909篇
  1985年   29184篇
  1984年   22445篇
  1983年   19648篇
  1982年   11902篇
  1981年   10832篇
  1979年   21271篇
  1978年   15727篇
  1977年   13096篇
  1976年   12107篇
  1975年   13083篇
  1974年   15850篇
  1973年   15580篇
  1972年   14696篇
  1971年   13713篇
  1970年   12927篇
  1969年   12190篇
  1968年   11355篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
OBJECTIVE: To evaluate the reproducibility of sonographic measurement of the lower uterine segment in pregnant women at term. METHODS: Two independent observers performed transabdominal sonography on 129 women between 36 and 38 weeks of gestation who had had a previous Cesarean section. Sonography was performed when the patients had a full and a half-full bladder; in 100 patients, the measurements were also performed transvaginally, with the patients having an empty bladder. Agreement was quantified by the intraclass correlation coefficient and, using a cut-off of 3.5 mm, by the kappa coefficient. RESULTS: The intraobserver agreement was generally high (intraclass correlation coefficient > 0.90). The interobserver agreement was higher on transvaginal (intraclass correlation coefficient, 0.94) compared with transabdominal (0.70 and 0.84, with full and half-full bladder, respectively) ultrasound. The kappa coefficient was 0.75 transvaginally, compared with 0.34 and 0.54 using the transabdominal approach, with full and half-full bladder, respectively. CONCLUSION: The agreement between two observers for sonographic transvaginal measurement of the lower uterine segment can be considered good, compared with poor to moderate agreement using the transabdominal approach.  相似文献   
53.
54.
AIMS: To examine the effects of agents that alter potassium adenosine triphosphate (KATP) channel activity in beta-cells on cognitive function and counterregulatory hormone responses during acute hypoglycaemia, given the physiological similarities between the pancreatic beta-cell and the hypothalamic glucose-sensitive neurones (GSN) and the widespread distribution of sulphonylurea receptors in neuronal cells throughout the brain. METHODS: Ten healthy males were studied on four occasions and in random order underwent three stepped hypoglycaemic (plasma glucose aims: 3.4, 2.8, 2.4 mmol/l) and one euglycaemic (plasma glucose aim: 5 mmol/l) insulin clamps. Prior to each hypoglycaemic study, volunteers received either 10 mg glibenclamide, or 5 mg/kg diazoxide or placebo orally. Cognitive function, symptom scores and counterregulatory hormone responses were measured at each glycaemic level. RESULTS: There was no statistically significant effect of either drug on the symptoms generated or the counterregulatory hormonal response during hypoglycaemia. However, cognitive function was better preserved during hypoglycaemia in the glibenclamide-treated arm, particularly four-choice reaction time which deteriorated at a plasma glucose 2.5 mmol/l compared with 3.0 mmol/l with diazoxide (P = 0.015) and 2.9 mmol/l with placebo (P = 0.114). CONCLUSIONS: Single doses of pharmacological agents which alter membrane KATP channel activity do not affect the counterregulatory response to hypoglycaemia but may modify cognitive function during cerebral glucopenia. The unexpected effects of glibenclamide on cortical function suggest a novel action of sulphonylureas that warrants further investigation.  相似文献   
55.
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males.  相似文献   
56.
57.
58.
Decreases in sex hormone levels with menopause may bring about a number of consequences in women's general health and sexual well-being, especially when levels decline suddenly and prematurely, as in surgical menopause. In addition to the well-established role of estrogens in preserving the biological basis of sexual response, there is emerging evidence that androgens are significant independent determinants affecting sexual desire, activity and satisfaction, as well as mood, energy and other components of women's health. Hypoactive sexual desire disorder (HSDD), a persistent absence of sexual fantasies or thoughts and/or desire for and receptivity to sexual activity that causes personal distress, is experienced by some postmenopausal women. Even though conventional hormone therapy with estrogens or estrogens and progestogens may be effective for vaginal atrophy, increasing vaginal lubrication and reducing dyspareunia, it has not been shown to consistently increase sexual desire or activity and many women with sexual dysfunction remain unresponsive. Several recent, large, phase III studies have shown that the addition of transdermal testosterone to conventional hormone therapy can be helpful in surgically menopausal women presenting with HSDD. After 24 weeks of treatment in these studies, testosterone-treated women experienced significantly greater increases in satisfying sexual activity and sexual desire, and greater decreases in distress, than placebo-treated women. Accurate clinical assessment and individualized management of sexual symptoms are fundamentally important for all menopausal women with HSDD or other sexual problems.  相似文献   
59.
We report a case of a prepubertal girl with juvenile primary hypothyroidism presenting as ovarian cysts and precocious puberty. The 7-year-old female was referred to our clinic because of a pelvic/abdominal mass and vaginal bleeding. Besides these findings, on physical examination we noticed the thyroid gland globally increased and the presence of secondary sexual characteristics. Based upon the clinical profile and investigations, the patient was diagnosed with juvenile primary hypothyroidism due to autoimmune thyroiditis. The cysts and precocious puberty resolved spontaneously after the simple replacement of thyroid hormone. It is important to bear in mind hypothyroidism in cases of girls presenting ovarian cysts and precocious puberty in order to avoid unnecessary surgery on the ovaries.  相似文献   
60.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号